diff --git a/Data/BinaryList/Serialize.hs b/Data/BinaryList/Serialize.hs
--- a/Data/BinaryList/Serialize.hs
+++ b/Data/BinaryList/Serialize.hs
@@ -113,6 +113,11 @@
   rnf (FinalResult   xs  b) = rnf xs  `seq` rnf b
   rnf (DecodingError str b) = rnf str `seq` rnf b
 
+instance Functor Decoded where
+  fmap f (PartialResult xs  d) = PartialResult (fmap f xs) $ fmap f d
+  fmap f (FinalResult   xs  b) = FinalResult   (fmap f xs) b
+  fmap _ (DecodingError str b) = DecodingError str b
+
 -- | Get the final result of a decoding process, unless it returned an error, in which
 --   case this error is returned as a 'String'.
 fromDecoded :: Decoded a -> Either String (BinList a)
diff --git a/binary-list.cabal b/binary-list.cabal
--- a/binary-list.cabal
+++ b/binary-list.cabal
@@ -1,5 +1,5 @@
 name:                binary-list
-version:             1.1.0.2
+version:             1.1.1.0
 synopsis:            Lists of length a power of two.
 description:         Implementation of lists whose number of elements is a
                      power of two. Binary lists have this property by definition,